Do ball valves ever leak?

Yes, ball valves can leak, although they are generally known for their reliability and tight sealing capabilities. Leaks usually occur in two places: externally from the stem packing or internally past the ball and seats. External leaks happen when the packing material around the stem wears out or loosens over time, allowing fluid to escape around the handle. This can often be fixed by tightening the packing nut or replacing the O-rings. Internal leaks occur when the valve is closed but water still passes through. This is typically caused by worn or damaged seats, scratches on the ball surface, or debris preventing the ball from seating properly. Over time, repeated use, high pressure, or exposure to corrosive fluids can degrade the sealing surfaces. While rare in new, high-quality valves, leaks become more common as the valve ages. Regular maintenance and proper installation can minimize the risk, but eventual replacement may be necessary if the internal components are severely worn.